Increased blood vessel formulation is a predictive factor in survival for a certain disease. One treatment is stem cell transplantation with the patient's own stem cells. The accompanying data table represents the microvessel density for patients who had a complete response to the stem cell transplant. The measurements were taken immediately prior to the stem cell transplant and at the time the complete response was determined. Complete parts (a) through (d) below. Click the icon to view the data table. a. At the 0.05 level of significance, is there evidence that the mean microvessel density is higher before the stem cell transplant than after the stem cell transplant? Let μ₁ be the mean density before the transplant and let μ₂ be the mean density after the transplant. State the null and alternative hypotheses. Choose the correct answer below. OA. Ho: HD <0 (where HD H1-H₂) H₁: HD 20 C. Ho: HD ≤0 (where HD=H1-H₂) H₁: HD>0 O E. Ho: HD 0 (where HD=H1-H₂) H₁: HD 0 The test statistic is tSTAT = - (Round to two decimal places as needed.) OB. Ho: HD >0 (where HD H1-H₂) H₁: HD ≤0 OD. Ho: HD 20 (where HD =H1-H₂) H₁: HD <0 OF. Ho: HD 0 (where HD H1-H₂) H₁ HD=0