Answer:
this is an example of B) Functional fixedness
Step-by-step explanation:
Functional fixedness - is one type of fixation that can work against solving a problem, focusing on familiar functions or uses of an object.
The reason why this is functional fixedness is because people's creative problem solving skills are limited and this leads to them ignoring other possible solutions to problems.
In the string problem, the aim was to tie the two pieces of strings together and the solution to that was to tie the screwdriver to one of the strings and swing it like a pendulum. While the string is swinging, you must then walk over to the other string.