The hydrocarbond tains of phospholipid a contain more double bonds than the hydrocarbon tails of phospholipid b. a membrane made of phospholipid a molecules will be than a membrane made of phospholipid b.

I think the correct answer from the choices listed above is option B.  A membrane made of Phospholipid A molecules will be less fluid than a membrane made of phospholipid B. It will have a higher viscosity than the latter type. Hope this answers the question. Have a nice day.