Calling Subscribe inside Foreach Angular

I’ve a survey which contains list of questions, where each question contains list of multiple choice answer. I’m trying to push this to my backend, but it’s pushing ONLY the first question of the survey according to my database. I made sure that the questions and the answers are inserted correctly and also i tested the mutation using Graphql

this._surveyService.addSurveyToInitiative(this._initiativeId, this.name, this.category, "TBD").subscribe(surveyData => {
     this.survey.questions.forEach(question => {
        this._surveyService.addQuestionToSurvey(surveyData.data.createSurvey.survey.id, question.question).subscribe(questionData=> {
          question.multipleChoiceAnswers.forEach(answer => {
            this._surveyService.addMultipleChoiceAnswerToQuestion(questionData.data.addQuestionToSurvey.newQuestion.id, answer).subscribe()
          })
        })
     })
   })
}

Source: Angular Questions