To solve this problem, we need to determine during which phase of mitosis spindle fibers attach to kinetochores of chromosomes. Let's analyze each phase:$\newline \bullet$Prophase:$\newline$ - During prophase, the chromatin condenses into visible chromosomes, and the mitotic spindle begins to form. However, spindle fibers do not yet attach to kinetochores.$\newline \bullet$Metaphase:$\newline$ - In metaphase, chromosomes align at the metaphase plate, and spindle fibers attach to the kinetochores of each chromosome. This is the phase where attachment occurs.$\newline \bullet$Anaphase:$\newline$ - During anaphase, the sister chromatids are pulled apart toward opposite poles of the cell. The attachment to kinetochores has already occurred by this phase.$\newline \bullet$Telophase:$\newline$ - In telophase, the chromosomes reach the poles, and the nuclear envelope re-forms around each set of chromosomes. Spindle fibers have already detached by this phase.$\newline$Therefore, the correct answer is that spindle fibers attach to kinetochores during metaphase.$\newline$This corresponds to Option 4.