Explanation: A typical modern computer uses LSI (Large-Scale Integration) chips, which are microchips that contain thousands or even millions of transistors on a single silicon chip. These chips are essential for performing the computer's functions, such as processing data, running programs, and managing input/output operations.

Here’s why the other options are incorrect:

(A) Magnetic cores for secondary storage: Magnetic core memory was used in older computers for primary memory, but modern computers use semiconductor-based memory like DRAM (Dynamic RAM) for primary storage, and hard drives or SSDs for secondary storage.

(C) Magnetic tape for primary memory: Magnetic tape is an outdated method of storage primarily used for backup or archival purposes, not for primary memory in modern computers.

(D) More than 10,000 vacuum tubes: Vacuum tubes were used in the early days of computing (like in the ENIAC), but modern computers rely on semiconductor-based components like transistors and LSI chips, not vacuum tubes.

So, LSI chips are what modern computers use for their processing needs.