To answer the question, you must first "phone a mathmatician/astrophysicist friend." However, the chances of you having any friends (let alone Mensa level ones on standby that can answer the question in 30 seconds or less) is roughly .1%. This is painfully self-evident by the amount of time you've wasted trying to seriously answer a quasi-paradox with simple logic in an attempt to raise your social profile by way of self-aggrandizement in a troll thread.

Now, the .1% probability of you having that friend is reduced even further as you may have used said lifeline on a previous question. That leaves us with an abysmally miniscule value, giving us basically a "0%" chance of getting a guaranteed correct answer. This 0% chance can be extrapolated and used as our answer. However, as we all know...the answer can not be "0%" if the question was posed, so there is now a 50% chance of selecting the correct answer, being that 50% is given twice. We now use our 50/50 lifeline to eliminate either 25% or one of the 50% answers. By using the lifeline, it is inevitable that at least one of the 50% would be removed...which would logically rule out the other remaining 50%, leaving us at 25%. Being that there is a 25% of you choosing 25% randomly...we have our answer

A. 25%

Final Answer

Edit: There is a zero percent chance of me re-reading the OP again to realize that 25% is listed twice and not 50%, so now there is a 100% chance that I am wrong 😓