Synthesize the timeline of implantation with the menstrual cycle and discuss its impact on the timing of pregnancy tests.

• A. Implantation prevents menstruation, detectable by day 14 of the cycle.
• B. Implantation occurs at the end of the cycle, making pregnancy tests ineffective until day 40.
• C. Implantation coincides with ovulation, allowing for immediate pregnancy detection.
• D. Implantation occurs around day 20-24 of the cycle, allowing HCG detection by day 28.

Answer: (D)