Raising the temperature of a reacting system increases the rate of the
reaction but does NOT increase the:
a. average velocity of the reacting molecules
b.fraction of reacting molecules that possess energies greater than
the activation energy.
c. activation energy

Hello teatea

The correct answer is A.  Raising the temperature will not increase
the activation energy.

An assignment on rates equilibrium analysis presented on the web site
of the Dr EP Scarlett Senior High School, Calgary has the following
question, very similar to yours:

. Raising the temperature of a reacting system increases the rate of
the reaction, but does not increase the
        A. activation energy 
        B. average velocity of the reacting molecules 
        C. number of collisions per second 
        D. number of successful collisions 
        E. fraction of the reacting molecules which possess energies
greater than the
            activation energy

Answer A is marked (by the text being in red) as the correct answer. 
http://schools.cbe.ab.ca/b858/dept/sci/teacher/yancey%5CReview.book%5CRa.Eq.Keys%5Cra.assign2.ans.html

Search strategy: raising temperature "average velocity" molecules
"activation energy"

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Clarification of Answer by tehuti-ga on 26 Jul 2003 18:40 PDT

Ah, my apologies, arsenic, I was looking at the list in the Calgary
question. Hopefully teatea has read the whole statement that the
activation energy is not increased.  Yes, that means that in teatea's
variant of the question the answer is C. My aplogies to you also
teatea.

The correct answer is 
Raising the temperature of a reacting system increases the rate of the
reaction but does NOT increase the:
c. activation energy

tehuti-ga, a small typo:) The correct answer to the q is C.

Excuse me arsenic, but you are terribly mistaken.  To quote yet
another source, this time from "Chemguide - Helping you to understand
Chemistry"
http://www.chemguide.co.uk/physical/basicrates/temperature.html

"If you increase the temperature from 293 K to 303 K (20°C to 30°C),
you will increase the collision frequency"

You obviously misread the question, which is asking what does NOT
increase on account of an increase in temperature. As stated in my
answer, and backed by a reliable educational source, activation energy
is the only one of the listed parameter that is not increased by an
increase in temperature.